1. Field of the Invention
The present invention relates generally to a reverse link communication device and method, and in particular, to a device and method for controlling transmission on a reverse link on the basis of a received signal strength on a forward link.
2. Description of the Related Art
A mobile communication system controls transmission/reception according to changes in channel environment to maintain system stability. To do so, a mobile station controls transmission on a reverse link by checking the status of a forward link. FIG. 1 is a block diagram of a conventional device for controlling reverse link communication by determining the status of a forward link in a mobile communication system. Here, the mobile communication system is assumed to be a CDMA (Code Division Multiple Access) communication system.
Referring to FIG. 1, an RF (Radio Frequency) module 111 down-converts the frequency of an RF signal received through an antenna to a baseband frequency. A receiver 113 despreads the baseband signal received from the RF module 111, accumulates the despread signal in symbol units, and determines the level of the accumulated symbols. Here, the despreading includes PN despreading and orthogonal despreading. A decoder 115 decodes the symbols received from the receiver 113. A CRC (Cyclic Redundancy Check) detector 117 generates a CRC detection signal indicating the presence or absence of frame errors, for the input of the decoded symbols. A controller 119 receives the output of the CRC detector 117 and generates a signal for controlling reverse link transmission. A transmitter 121 is a reverse link channel transmitter of which the transmission is controlled by the control signal received from the controller 119.
As shown in FIG. 1, the conventional reverse link transmission controlling method controls transmission on the reverse link by calculating a CRC in a frame. If the CRC detector 117 detects CRC errors in more than a predetermined number of successive frames, the controller 119 generates a control signal for controlling the transmitter 121 to stop reverse link transmission. In other words, if frames are determined to be damaged through the CRC error check, the channel environment of a forward link is assumed to be bad and transmission on the reverse link is suspended.
The above conventional method can be adapted only to a frame data transmission period on the forward link channel. Therefore, a CRC error check is useless during a non-frame data transmission period on the forward link, for example, in a discontinuous transmission (DTX) mode using channel. Accordingly, a need exists to control reverse link transmission during a non-transmission period by checking the channel status of the forward link as observed on a DTX mode using channel.